For most of the DUP's history, the
Ulster Unionist Party was the largest unionist party in Northern Ireland, but by 2004 the DUP had overtaken the UUP in terms of seats in the Northern Ireland Assembly and
Parliament. Following the
St Andrews Agreement in 2006, the DUP agreed to enter into
power-sharingdevolved government in Northern Ireland with
Sinn Féin. Despite reports of divisions within the party, a majority of the party executive voted in favour of power-sharing in 2007.[13] However, the DUP's sole Member of the European Parliament (MEP),
Jim Allister,[14] and seven DUP councillors[15] left the party in opposition to its plans to share power with Sinn Féin, founding the
Traditional Unionist Voice.[16]Peter Robinson became DUP leader in 2008. Under his leadership, the loyalist influence reduced somewhat, in an attempt to reach out to non-Protestants, particularly socially conservative
Catholics[17][18] and
Catholic unionists.

Following the downfall of the Agreement, in 1975 the British government set up a
Constitutional Convention, an elected body of unionists and nationalists which would seek agreement on a political settlement for Northern Ireland. In the election to the Convention, the UUUC (which included the DUP) won 53% of the vote. The UUUC opposed a power-sharing government and recommended only a return to majority rule (i.e. unionist rule). As this was unacceptable to nationalists, the Convention was dissolved.[26]

The DUP opposed UK membership of the
European Economic Community (EEC). In June 1979, in the
first election to the
European Parliament, Paisley won one of the three Northern Ireland seats. He topped the poll, with 29.8% of the first preference votes.[27] He retained that seat in every European election until 2004, when he was replaced by
Jim Allister, who resigned from the DUP in 2007 while retaining his seat.[14]

1980s and 1990s

During 1981, the DUP opposed the then-ongoing talks between British Prime Minister
Margaret Thatcher and Irish Prime Minister
Charles Haughey. That year, Paisley and other DUP members attempted to create a Protestant loyalist volunteer
militia—called the (Ulster)
Third Force—which would work alongside the police and army to fight the
Irish Republican Army (IRA). They organized large rallies where men were photographed in military formation waving
firearms certificates. Paisley declared: "This is a small token of the men who are placed to devastate any attempt by Margaret Thatcher and Charles Haughey to destroy the Union".[28] The DUP helped organize a loyalist 'Day of Action' on 23 November 1981, to pressure the British government to take a harder line against the IRA.[29] Paisley addressed a Third Force rally in
Newtownards, where thousands of masked and uniformed men marched before him. He declared: "My men are ready to be recruited under the crown to destroy the vermin of the IRA. But if they refuse to recruit them, then we will have no other decision to make but to destroy the IRA ourselves!"[30] In December, Paisley claimed that the Third Force had 15,000–20,000 members.
James Prior,
Secretary of State for Northern Ireland, replied that private armies would not be tolerated.[29]

The
Anglo-Irish Agreement was signed by the British and Irish governments in November 1985, following months of talks between the two. The Agreement confirmed there would be no change in the status of Northern Ireland without
the consent of a majority of its citizens, and proposed the creation of a new power-sharing government. It also gave the Irish government an advisory role on some matters in Northern Ireland. Both the DUP and UUP mounted a major protest campaign against the Agreement, dubbed "
Ulster Says No". Both unionist parties resigned their seats in the British House of Commons, suspended district council meetings, and led a campaign of mass
civil disobedience. There were strikes and mass protest rallies.[31]

On 23 June 1986, DUP politicians occupied the
Stormont Parliament Building in protest at the Agreement, while 200 supporters protested outside and clashed with police.[31] The DUP politicians were forcibly removed by police the next day.[31] On 10 July, Paisley and deputy DUP leader Peter Robinson led 4,000 loyalist supporters in a protest in which they 'occupied' the town of
Hillsborough.
Hillsborough Castle is where the Agreement had been signed.[31] On 7 August, Robinson led hundreds of loyalist supporters in
an invasion of the village of
Clontibret, in the Republic of Ireland. The loyalists marched up and down the main street, vandalised property, and attacked two Irish police officers (
Gardaí) before fleeing back over the border. Robinson was arrested and convicted for
unlawful assembly.[32]

On 10 November 1986, a rally was held in which DUP politicians Paisley, Robinson and
Ivan Foster announced the formation of the
Ulster Resistance Movement (URM). This was a loyalist paramilitary group whose purpose was to "take direct action as and when required" to bring down the Agreement and defeat republicanism.[33] Recruitment rallies were held in towns across Northern Ireland and thousands were said to have joined.[33] The following year, the URM helped smuggle a large shipment of weapons into Northern Ireland, which were shared out between the URM, the
Ulster Volunteer Force (UVF) and the
Ulster Defence Association (UDA). Most, but not all, of the weaponry was seized by police in 1988. In 1989, URM members attempted to trade
Shorts' missile blueprints for weapons from the
apartheidSouth African regime. Following these revelations, the DUP said that it had cut its links with the URM in 1987.[34]

In the mid-1980s, the Irish republican party
Sinn Féin began to contest and win seats in local council elections. In response, the DUP fought elections under the slogan "Smash Sinn Féin" and vowed to exclude Sinn Féin councillors from all council business. Their 1985 manifesto said "The Sinn Féiners must be ostracised and isolated" at all local government bodies. Throughout the 1980s and 1990s, DUP councillors attempted to exclude Sinn Féin councillors by ignoring them, boycotting their speeches, or drowning them out by making as much noise as possible – such as by heckling and banging tables.[35]

In early January 1994, the Ulster Defence Association released a document calling for the
repartition of Ireland with the goal of making Northern Ireland wholly Protestant.[36] The plan was to be implemented should the British Army withdraw from Northern Ireland. The Irish Catholic/nationalist-majority areas would be handed over to the Republic, and those left in the rump state would be "expelled,
nullified, or
interned".[36]Sammy Wilson, then a DUP press officer and a future
Stormont minister and
MP, spoke positively of the document, calling it a "valuable return to reality" and lauded the UDA for "contemplating what needs to be done to maintain our separate Ulster identity".[36]

The DUP contested the
1998 Northern Ireland Assembly election that resulted from the Good Friday Agreement, winning 20 seats, the third-highest of any party. It then took up two of the ten seats in the multi-party power-sharing Executive. While serving as ministers, they refused to sit at meetings of the Executive Committee in protest at Sinn Féin's participation.[citation needed] The Executive ultimately collapsed over an alleged IRA espionage ring at
Stormont (see
Stormontgate).

The Good Friday Agreement relied on the support of a majority of unionists and a majority of nationalists in order for it to operate.[citation needed] During the
2003 Northern Ireland Assembly election, the DUP argued for a "fair deal" that could command the support of both unionists and nationalists. After the results of this election the DUP argued that support was no longer present within unionism for the Good Friday Agreement. They went on to publish their proposals for devolution in Ireland entitled Devolution Now.[37] These proposals have been refined and re-stated in further policy documents including Moving on[38] and Facing Reality.[39]

In the 2003 Northern Ireland Assembly election, the DUP won 30 seats, the most of any party. In January 2004, it became the largest Northern Ireland party at
Westminster, when MP
Jeffrey Donaldson joined after defecting from the UUP. In December 2004, English MP
Andrew Hunter took the DUP whip after earlier withdrawing from the
Conservative Party, giving the party seven seats, in comparison to the UUP's five, Sinn Féin's four, and the
Social Democratic and Labour Party's (SDLP) three

2005–2007

In the
2005 UK general election, the party reinforced its position as the largest unionist party, winning nine seats, making it the fourth largest party in terms of seats in the British House of Commons behind Labour, the Conservatives and the Liberal Democrats. In terms of votes, the DUP was the fourth largest party on the island of Ireland.

On 27 October 2006, the DUP issued a four-page letter in the Belfast Telegraph newspaper asking "Are the terms of Saint Andrew's a basis of moving forward to devolution?", with responses to be received to its party headquarters by 8 November. It was part of the party's policy of consultation with its electorate before entering a power-sharing government.[citation needed]

On 24 November 2006, Ian Paisley refused to nominate himself as
First Minister of Northern Ireland designate. There was confusion between all parties whether he actually said that if Sinn Féin supported policing and the rule of law that he would nominate himself on 28 March 2007 after the Assembly elections on 7 March 2007. The Assembly meeting was brought to an abrupt end when the building had to be evacuated because of a security breach. Paisley later released a statement through the press office stating that he did in fact imply that if Sinn Féin supported policing and the rule of law, he would go into a power-sharing government with them. This was following a statement issued by 12 DUP MLAs stating that what Ian Paisley had said in the chamber could not be interpreted as a nomination.[41]

In February 2007, the DUP suggested that it would begin to impose fines up to
£20,000 on members disobeying the party whip on crucial votes.[42] On 24 March 2007 the DUP party executive overwhelmingly endorsed a resolution put to them by the party officers that did not agree to an establishment of devolution and an executive in Northern Ireland by the Government's deadline of 26 March, but did agree to setting up an executive on 8 May 2007.[13]

On 27 March 2007, the party's sole Member of the European Parliament (MEP),
Jim Allister, resigned from the party, in opposition to the decision to enter a power-sharing government with Sinn Féin. He retained his seat as an independent MEP as leader of his new hard-line anti-St Andrews Agreement splinter group that he formed with other disaffected members who had left the DUP over the issue,
Traditional Unionist Voice, a seat which he retained until
Diane Dodds won the seat back for the DUP in 2009. MP
Gregory Campbell warned on 6 April 2007 that his party would be watching to see if benefits flow from its agreement to share power with Sinn Féin.[43]

Robinson leadership

Peter Robinson, the party's deputy leader from 1980 and its leader from 2008–2015

On 31 May 2008, the party's central Executive Committee met at the offices of
Castlereagh Borough Council where Ian Paisley formally stepped down as party leader and Peter Robinson was ratified as the new leader, with Nigel Dodds as his deputy.

On 11 June 2008, the party supported the government's proposal to detain terrorist suspects for up to 42 days as part of the
Counter-Terrorism Bill, leading The Independent newspaper to dub all of the party's nine MPs as part of "Brown's dirty dozen".[44]The Times reported that the party had been given "sweeteners for Northern Ireland" and "a peerage for the Rev Ian Paisley", amongst other offers, to secure the bill.[45]

Members of the DUP were lambasted by the press and voters, after MPs' expenses reports were leaked to the media. Several newspapers referred to the "Swish Family Robinson" after Peter Robinson, and his wife Iris, claimed £571,939.41 in expenses with a further £150,000 being paid to family members.[46] Further embarrassment was caused to the party when its deputy leader, Nigel Dodds, had the highest expenses claims of any Northern Ireland MP, ranking 13th highest out of all UK MPs.[47] Details of all MPs' expenses claims since 2004 were published in July 2009 under the
Freedom of Information Act 2000.

In January 2010, Peter Robinson was at the centre of a
high-profile scandal relating to his 60-year-old MP/MLA wife
Iris Robinson's infidelity with a 19-year-old man, and alleged serious financial irregularities associated with the scandal.[48][49]

The DUP were strongly criticised after the
Red Sky scandal in which DUP ministers attempted to influence a decision at a meeting of the
Northern Ireland Housing Executive. The decision related to a £8 million contract of east Belfast firm Red Sky. The Housing Executive cancelled Red Sky's contract after a BBC Spotlight investigation into the company, which was shown to be overcharging taxpayers. The DUP cited "sectarian bias" in relation to the decision.[50] The party suspended DUP councillor
Jenny Palmer, who sat on the Executive board, after she confessed that DUP special adviser Stephen Brimstone pressured her into changing her vote at the meeting.

In the
2015 general election, when the result was expected to be a
hung parliament, the issue of DUP and the
UK Independence Party forming a
coalition government with the
UK Conservative Party was considered by
Nigel Farage (leader of UKIP).[51][52] The then Deputy Prime Minister and leader of the
Liberal Democrats,
Nick Clegg, warned against this "Blukip" coalition, with a spoof website highlighting imagined policies from this coalition – such as reinstating the
death penalty, scrapping all benefits for under 25s and charging for hospital visits.[53] Additionally, issues were raised about the continued existence of the
BBC (as the DUP, UKIP and Conservatives had made a number of statements criticising the institution)[54] and support for
LGBT rights and
same-sex marriage.[55][56] However, in an interview with
BBC Radio 5 Live deputy leader of the DUP
Nigel Dodds told
BBC Newsline in 2015 that, despite opposition to same-sex marriage, the DUP was "against discrimination based on religion ... or sexual orientation".[56] Additionally, David Cameron said he "totally disagreed" with the DUP on the issue of same-sex marriage and LGBT rights, claiming that "nothing I will do" would go against the principle of "the values that I have", including "equality for gay and lesbian people".[57]

On 10 September 2015, Peter Robinson stepped aside as First Minister and other DUP ministers, with the exception of
Arlene Foster, resigned their portfolios.[58]

Foster leadership

Arlene Foster became leader of the DUP on 17 December 2015.

Two days before the
UK Brexit referendum, held on 23 June 2016, the DUP paid £282,000 for a four page glossy wrap-around to the free newspaper Metro, which is distributed for free in major towns and cities in the British mainland, but not Northern Ireland, advocating a 'Leave' vote.[59]

On 4 October 2016, DUP leader Arlene Foster and DUP MPs held a champagne reception at the
Conservative Partyconference, marking what some have described as an "informal coalition" or an "understanding" between the two parties to account for the Conservatives' narrow majority in the
House of Commons.[60][61]

In her capacity as Minister of Enterprise, Trade and Investment in 2012, Foster oversaw the establishment of a
green energy scheme, which led to the
Renewable Heat Incentive scandal. The scheme gave a
perverse incentive to use more energy and increase their
carbon footprint to those who signed up to it since they could claim £1.60 for every £1 spent on heating with, for example, wood pellets.[62] With no cost controls, it could cost the public purse up to £490 million.

In the
UK 2017 general election, the DUP had 10 seats overall, 3 seats ahead of Sinn Féin.[64] With no party having received an outright majority in the UK Parliament, the DUP entered into
an agreement to support
government by the
Conservative Party.[65] A DUP source said: "The alternative is intolerable. For as long as Corbyn leads Labour, we will ensure there’s a Tory PM."[65]